The present invention generally relates to semiconductor devices and methods of producing the same, and to semiconductor device units and methods of producing the same. More particularly, the present invention relates to a semiconductor device which encapsulates a semiconductor element by a resin and to a method of producing such a semiconductor device, and to a semiconductor device unit and a method of producing the semiconductor device unit.
Recently, there are demands to further reduce the size of electronic equipments such as personal computers, and as a result, there are increased demands to realize smaller semiconductor devices which are used in such electronic equipments.
In semiconductor devices, a substrate which holds a semiconductor element or the volume of an encapsulating resin is large compared to the size of the semiconductor element. For this reason, in order to reduce the size of the semiconductor device, it is necessary to appropriately reduce the size of the substrate or the encapsulating resin.
On the other hand, when the size of the semiconductor device is reduced, the heat radiation characteristic of the semiconductor device deteriorates. As a result, it is necessary to provide an efficient heat radiation means.
Therefore, there are demands to realize a semiconductor device which has a reduced size but can be formed with ease and has a satisfactory heat radiation characteristic.
A description will be given of an example of a conventional semiconductor device and a method of producing the same, by referring to FIGS. 1A through 1C. FIGS. 1A through 1C respectively show cross sections of the conventional semiconductor device at various stages of the production process.
As shown in FIG. 1C, a conventional semiconductor device 60 includes a semiconductor element 1, a mold resin 3, a lead frame 46 and the like. The semiconductor element 1 is die-bonded on a die-pad portion 39 which is formed on the lead frame 46. In addition, wires 10 are provided between electrode pad portions 40 on the top surface of the semiconductor element 1 and inner lead portions of the lead frame 46. The electrode pad portions 40 are shown in FIG. 1A. The mold resin 3 encapsulates the semiconductor element 1, the wires 10 and the inner lead portions of the lead frame 46, so as to protect the semiconductor element 1 and the wires 10.
The mold resin 3 is formed as shown in FIG. 1B. In FIG. 1B, an upper mold 20a and a lower mold 20b form a transfer mold. When the lead frame 46 mounted with the semiconductor element 1 and having the wires 10 bonded thereto as shown in FIG. 1A is loaded between the upper and lower molds 20a and 20b. 
A plunger 22 arranged on the upper mold 20a heats and presses a resin tablet (mold resin 3) which is indicated by a dot-pattern, so that the melted resin tablet flows into a cavity part formed between the upper and lower molds 20a and 20b via a cull part 43, a runner part 44 and a gate part 45. The cavity formed between the upper and lower molds 20a and 20b has a shape corresponding to the outer shape of the semiconductor device 60. Hence, by filling the rein into this cavity part, the mold resin 3 is formed into a package having a predetermined shape.
According to the conventional resin filling method, the mold resin 3 remains at the cull part 43, the runner part 44 and the gate part 45, integrally to the package part of the semiconductor device 60. Accordingly, when the semiconductor device 60 is removed from the upper and lower molds 20a and 20b , the remaining resin is broken at the gate part 45 and the broken off resin is thrown away.
On the other hand, as is well known, the semiconductor element 1 generates heat when driven. In the case of the semiconductor device 60 which is produced in the above described manner, the heat generated from the semiconductor element 1 thermally conducts via the mold resin 3, and the heat radiation takes place particularly at the back surface of the package where the thickness of the mold resin 3 is thin. The back surface of the package is the bottom surface of the mold resin 3 in FIG. 1C.
As described above, the main function of the mold resin 3 is to protect the semiconductor element 1 and the wires 10. However, the mold resin 3 must also have a satisfactory adhesive strength. In other words, if the adhesive strength of the mold resin 3 with respect to the semiconductor element 1 and the wires 10 provided within the mold resin 3 is weak, the semiconductor element 1 and the wires 10 may move within the package. If the semiconductor element 1 and the wires 10 move within the package, it becomes impossible to positively protect the semiconductor element 1 and the wires 10, and the reliability of the semiconductor device 60 will deteriorate.
But when carrying out the transfer molding, it is essential to separate the upper and lower molds 20a and 20b from the molded package, and the upper and lower molds 20a and 20b can be separated more satisfactorily if the above adhesive strength is not too strong. For this reason, a mold release agent which facilitates the separation of the upper and lower molds 20a and 20b is conventionally added to the mold resin 3. The kind and quantity of this mold release agent that is to be added are selected to optimize the balance between the reliability of the semiconductor device 60 and the mold release (or parting) characteristic of the upper and lower molds 20a and 20b with respect to the molded package. More particularly, out of the cull part 43, the runner part 44 and the gate part 45, the mold release characteristic is poorest at the gate part 45 where the flow passage of the mold resin 3 is the narrowest. Hence, the kind and quantity of the mold release agent to be added are generally selected with reference to the mold release characteristic at the gate part 45.
However, as the size of the semiconductor device 60 is further reduced and the package becomes smaller, the cull part 43, the runner part 44 and the gate part 45 all become smaller, thereby deteriorating the mold release characteristic. For this reason, it is necessary to increase the amount of the mold release agent that facilitates the mold release as the package becomes smaller, but there was a problem in that the reliability of the semiconductor device 60 deteriorates if the amount of the mold release agent is increased for the reasons described above.
On the other hand, as for the heat radiation characteristic, the conventional semiconductor device 60 is designed to radiate heat via the back surface of the package. For this reason, there was a problem in that the heat generated from the semiconductor element 1 could not be released efficiently. In addition, there have been proposals to provide a plurality of radiator fins independently on the package, but the provision of the radiator fins increases the overall size of the semiconductor device 60, and there was a problem in that the provision of the independent radiator fins cannot realize the size reduction of the semiconductor device 60.
Accordingly, it is a general object of the present invention to provide a novel and useful semiconductor device and a method of producing the same, wherein the problems described above are eliminated.
Another and more specific object of the present invention is to provide a semiconductor device which can be made small while at the same time improving the mold release characteristic and the reliability of the semiconductor device, and to a method of producing such a semiconductor device.
It is also an object of the present invention is to provide a semiconductor device unit which can be made small while at the same time improving the mold release characteristic and the reliability of the semiconductor device unit, and to a method of producing such a semiconductor device unit.
Still another object of the present invention is to provide a semiconductor device which can be made small while at the same time realizing a satisfactory heat radiation characteristic, and to a method of producing such a semiconductor device.
A further object of the present invention is to provide a semiconductor device comprising a substrate having top and bottom surfaces, a semiconductor element mounted on the top surface of the substrate, and a resin package made of a resin and encapsulating the semiconductor element, where the substrate includes at least one resin gate hole enabling the resin to be introduced from the bottom surface of the substrate via the resin gate hole when encapsulating the semiconductor element by the resin. According to the semiconductor device of the present invention, it is possible to directly introduce the resin onto the substrate via the resin gate hole in the substrate when encapsuating the semiconductor element by the resin. Hence, it becomes unnecessary to provide a cull part, a runner part, a gate part and the like in the molds that is used for the resin mold. In addition, it is possible to reduce the contact area between the resin and the molds, and the kind and amount of mold release agent to be added to the resin may be selected without taking into account the mold release characteristic. As a result, it becomes possible to use a resin having a large adhesive strength, and the reliability of the semiconductor device can be improve even when the size of the semiconductor device is reduced.
Another object of the present invention is to provide a semiconductor device comprising a circuit, a semiconductor element having a top surface and mounted on the circuit, a frame body provided on the circuit and surrounding the semiconductor element in a state where a gap is formed between the semiconductor element and the frame body, and a resin package made of a resin filled on an inner side of the frame body and encapsulating the semiconductor element, where the frame body includes a resin gate hole which opens at a surface other than a surface confronting the top surface of the semiconductor element and enables the resin to be introduced on the inner side of the frame body via the resin gate hole when encapsulating the semiconductor element by the resin. According to the semiconductor device of the present invention, it is possible to reduce the contact area of the rein and the molds, because the semiconductor element is encapsulated by the resin by introducing the resin on the inner side of the frame body via the resin gate hole that opens at the surface of the circuit other than the surface confronting the top surface of the semiconductor element. Hence, the kind and amount of mold release agent to be added to the resin may be selected without taking into account the mold release characteristic. Therefore, it is possible to use a resin having a high adhesive strength, and the reliability of the semiconductor device can be improved even when the size of the semiconductor device is reduced.
Still another object of the present invention is to provide a method of producing a semiconductor device comprising the steps of (a) forming a resin gate hole penetrating a substrate and arranging wiring layers on a predetermined surface of the substrate, (b) mounting a semiconductor element on the predetermined surface of the substrate and electrically connecting the semiconductor element and the wiring layers, (c) loading the substrate mounted with the semiconductor element into molds so that an end of the resin gate hole opposite to the predetermined surface of the substrate faces a plunger pot of the molds, and filling a resin supplied from the plunger pot to a side of the substrate mounted with the semiconductor element via the resin gate hole, and (d) forming external connecting terminals on the circuit, the external connecting terminals being used to electrically connect the semiconductor device to an outside element. According to the method of the present invention, it is possible to directly introduce the resin onto the substrate via the resin gate hole in the substrate when encapsuating the semiconductor element by the resin. Hence, it becomes unnecessary to provide a cull part, a runner part, a gate part and the like in the molds that is used for the resin mold. In addition, it is possible to reduce the contact area between the resin and the molds, and the kind and amount of mold release agent to be added to the resin may be selected without taking into account the mold release characteristic. As a result, it becomes possible to use a resin having a large adhesive strength, and the reliability of the semiconductor device can be improve even when the size of the semiconductor device is reduced.
A further object of the present invention is to provide a method of producing a semiconductor device comprising the steps of (a) forming a substrate which makes contact with side surfaces of a semiconductor element and surrounds the semiconductor element to hold the semiconductor element, (b) providing a circuit electrically connected to the semiconductor element and having external connecting terminals for electrically connecting the semiconductor element to an outside element, and (c) encapsulating the semiconductor element by a resin. According to the method of the present invention, the contact area between the semiconductor element and the substrate is large because the substrate surrounds the semiconductor element. For this reason, it is possible to positively release the heat generated from the semiconductor element via the substrate, and the heat radiation characteristic of the semiconductor element can be improved. In addition, since the substrate for holding the semiconductor element is used to release the heat generated from the semiconductor element, it is possible to prevent the size of the semiconductor device from increasing.
Another object of the present invention is to provide a method of producing a semiconductor device comprising the steps of (a) forming a plurality of divided substrates forming a substrate, (b) forming the substrate which surrounds a semiconductor element by bonding the divided substrates to the semiconductor element using a bond material, (c) providing a circuit on the substrate and electrically connecting the circuit and the semiconductor element, (d) loading the substrate mounted with the semiconductor element into molds having a plunger pot, and filling a resin supplied from the plunger pot so as to encapsulate a surface of the semiconductor element electrically connected to the circuit, and (e) forming external connecting terminals on the circuit, where the external connecting terminals are used to electrically connect the semiconductor device to an outside element. According to the method of the present invention, it is possible to directly introduce the resin onto the substrate via the resin gate hole in the substrate when encapsuating the semiconductor element by the resin. Hence, it becomes unnecessary to provide a cull part, a runner part, a gate part and the like in the molds that is used for the resin mold. In addition, it is possible to reduce the contact area between the resin and the molds, and the kind and amount of mold release agent to be added to the resin may be selected without taking into account the mold release characteristic. As a result, it becomes possible to use a resin having a large adhesive strength, and the reliability of the semiconductor device can be improve even when the size of the semiconductor device is reduced.
Another object of the present invention is to provide a semiconductor device comprising a semiconductor element, a holding substrate holding the semiconductor element, a frame body provided on the holding substrate so as to surround the semiconductor element, where the frame body has a hole which communicates to a space formed between the holding substrate and the frame body and the frame body and the holding substrate form a housing, a plurality of leads having inner lead portions connected to the semiconductor element and outer lead portions extending outside the frame body, and a resin filling the space and encapsulating the semiconductor element and the inner lead portions, where all of the outer lead portions extend outside the housing from one side of the housing. According to the semiconductor device of the present invention, all of the leads extend outwards from the same side of the housing, and thus, it is possible to mount the semiconductor device in a standing position and improve the mounting density of the semiconductor device with respect to a mounting substrate.
Still another object of the present invention is to provide a semiconductor device unit comprising a plurality of semiconductor devices, and means for connecting the semiconductor devices in a stacked arrangement having a common surface, where each of the semiconductor devices comprise a semiconductor element, a holding substrate holding the semiconductor element, a frame body provided on the holding substrate so as to surround the semiconductor element, the frame body having a hole which communicates to a space formed between the holding substrate and the frame body, the frame body and the holding substrate forming a housing, a plurality of leads having inner lead portions connected to the semiconductor element and outer lead portions extending outside the frame body, and a resin filling the space and encapsulating the semiconductor element and the inner lead portions, where all of the outer lead portions extend outside the housing from one side of the housing, and all of the outer lead portions of each of the semiconductor devices extend from the common surface. According to the semiconductor device unit of the present invention, it is possible to improve the mounting density of the semiconductor devices with respect to a mounting substrate because a plurality of semiconductor devices can be mounted in the standing position.
A further object of the present invention is to provide a semiconductor device comprising a semiconductor element, a semiconductor element mounting substrate having a first surface mounted with the semiconductor element, a flexible wiring substrate wrapped around the semiconductor element mounting substrate, the flexible wiring substrate including a flexible base member, electrode portions formed on the base member and electrically connected to the semiconductor element, external connecting terminal portions formed on the base member and electrically connectable to an outside member, and wiring portions formed on the base member and electrically connecting the electrode portions and the external connecting terminal portions, and a resin encapsulating at least the semiconductor element. According to the semiconductor device of the present invention, the semiconductor element mounting substrate simply needs to have the function of supporting the semiconductor element mounted thereon, and the electrical connection between the semiconductor element and the external connecting terminals is made by the electrode portions, the external connecting terminal portions and the wiring portions of the flexible wiring substrate. Because the flexible wiring substrate is relatively inexpensive, it is possible to reduce the cost of the semiconductor device. In addition, the wiring can be drawn around with ease since the flexible wiring substrate wraps the semiconductor element mounting substrate inside and is arranged so that the electrode portions are automatically located adjacent to the semiconductor element and the external connecting terminal portions can be located at the bottom surface of the semiconductor element mounting substrate. Furthermore, the provision of the flexible wiring substrate does not interfere with the size reduction of the semiconductor device because the flexible wiring substrate is wrapped around the semiconductor element mounting substrate, and the semiconductor device can be made small.
Another object of the present invention is to provide a semiconductor device comprising a semiconductor element, a flexible wiring substrate wrapped around the semiconductor element, the flexible wiring substrate including a flexible base member, electrode portions formed on the base member and electrically connected to the semiconductor element, external connecting terminal portions formed on the base member and electrically connectable to an outside member, and wiring portions formed on the base member and electrically connecting the electrode portions and the external connecting terminal portions, and a resin encapsulating at least the semiconductor element. According to the semiconductor device of the present invention, it is possible to realize the so-called chip size package because the flexible wiring substrate is wrapped directly around the semiconductor element, and the semiconductor device can be made small.
Still another object of the present invention is to provide a semiconductor device comprising a semiconductor element, a semiconductor element mounting substrate having a first surface mounted with the semiconductor element, a second surface opposite to the first surface, a base member made of an insulator material, and a single-level first lead wiring layer formed on the second surface, wires electrically connecting the semiconductor element and the first lead wiring layer, a resin encapsulating the semiconductor element, and mechanical bumps formed on the first lead wiring layer as external connecting terminals and electrically connectable to an outside member. According to the semiconductor device of the present invention, it is possible to form the mechanical bumps with ease because the first lead wiring layer on which the mechanical bumps are formed is formed on the surface of the base member different from the surface on which the semiconductor element is mounted and the first lead wiring layer has a single-level structure.
A further object of the present invention is to provide a method of producing a semiconductor device unit comprising the steps of (a) providing a semiconductor element on a holding substrate which has a resin filling hole penetrating the holding substrate so that the holding substrate holds the semiconductor element, (b) providing leads on the holding substrate so that outer lead portions of the leads are intensively located only along one side of the holding substrate, (c) providing a frame body on the holding substrate with the leads so that the holding substrate surrounds the semiconductor element, (d) electrically connecting the semiconductor element and the leads, (e) filling a resin into a space formed between the holding substrate and the frame body via the resin filling hole so as to encapsulate the semiconductor element by the resin, and (f) stacking a plurality of semiconductor devices formed by the steps (a) through (e) to produce a semiconductor device unit having a common surface from which the outer lead portions of the semiconductor devices extend outwards. According to the method of the present invention, it is possible to make the resin encapsulation without the use of a complicated mold, because the resin is filled into the space formed by the holding substrate and the frame body via the resin filling hole. The resin encapsulating process can thus be carried out efficiently at a low cost.
Another object of the present invention is to provide a method of producing a semiconductor device unit comprising the steps of (a) providing a semiconductor element on a holding substrate which has a resin filling hole penetrating the holding substrate so that the holding substrate holds the semiconductor element, (b) providing leads on the holding substrate so that outer lead portions of the leads are intensively located only along one side of the holding substrate, (c) providing a frame body on the holding substrate with the leads so that the holding substrate surrounds the semiconductor element, (d) electrically connecting the semiconductor element and the leads, (e) stacking a plurality of semiconductor device assemblies formed by the steps (a) through (d) to form a stacked structure having a common surface from which the outer lead portions of the semiconductor device assemblies extend outwards, and (f) filling a resin in one operation into each space between adjacent semiconductor device assemblies of the stacked structure and into each space formed between the holding substrate and the frame body of each of the semiconductor device assemblies via the resin filling hole in at least one of the semiconductor device assemblies so as to encapsulate the semiconductor element of each of the semiconductor device assemblies by the resin, thereby producing a semiconductor device unit. According to the method of the present invention, the resin can be filled in one operation into the spaces between the adjacent semiconductor device assemblies after the semiconductor device assemblies are stacked. Thus, the resin encapsulating process can be carried out efficiently.
Still another object of the present invention is to provide a method of producing a semiconductor device comprising the steps of (a) forming a flexible wiring substrate from a flexible base member by providing electrode portions, external connecting terminal portions electrically connectable to an outside member, and wiring portions electrically connecting the electrode portions and the external connecting terminal portions on the flexible base member, (b) wrapping a semiconductor element mounting substrate inside by the flexible wiring substrate by bending the flexible wiring plate along the semiconductor element mounting substrate, (c) mounting a semiconductor element on the semiconductor element mounting substrate and electrically connecting the semiconductor element and the electrode portions of the flexible wiring substrate, (d) forming external connecting terminals on the external connecting terminal portions of the flexible wiring substrate, and (e) encapsulating the semiconductor element by a resin to produce the semiconductor device. According to the method of the present invention, the electrode portions, the external connecting terminal portions and the wiring portions can be formed on the base member using the printed wiring technique, for example. In addition, the semiconductor element mounting substrate can be wrapped by flexible wiring substrate by a simple process of bending the flexible wiring substrate along the semiconductor element mounting substrate. As a result, the semiconductor device can be produced at a low cost.
A further object of the present invention is to provide a method of producing a semiconductor device comprising the steps of (a) forming a semiconductor element mounting substrate by forming a semiconductor arranging hole and wire inserting holes at predetermined positions of a base member which is made of an insulator material, providing a conductive material on one surface of the base member, forming a single first lead wiring layer by patterning the conductive material into a predetermined pattern, and forming mechanical bumps on the first lead wiring layer for use as external connecting terminals, (b) mounting a semiconductor element on the semiconductor element mounting substrate and electrically connecting the semiconductor element and the first lead wiring layer by providing wires between the semiconductor element and the first lead wiring layer via the wire inserting holes, and (c) encapsulating the semiconductor element by a resin. According to the method of the present invention, the process of forming the semiconductor arranging hole and the wire inserting holes, the process of forming and patterning the first lead wiring layer, and the process of forming the mechanical bumps can all be carried out with ease. In addition, the process of providing the wires can easily be made by use of a general wire-bonding equipment. Further, known techniques such as potting and molding may be employed to carry out the resin encapsulating process. Therefore, the semiconductor device can be produced with a high production efficiency.
Other objects and further features of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings.